The present disclosure herein relates to a detection system, and more particularly to, a device for detecting a change in an underground medium using an arrival time of an ultrasonic signal.
A patent related to a method of measuring a position by using a difference in transmission time is disclosed in U.S. Patent Publication No. US 2014/00112104 A1 (ULTRASONIC LOCATION USING ONLY TIME DIFFERENCE OF ARRIVAL MEASUREMENTS). The above invention discloses a method of measuring a position by using a transmission delay time of an ultrasonic signal.
Also, a research topic on the water leak measurement of an underground conduit has been studied. T. Hao (Condition assessment of the buried utility service infrastructure, Tunneling and Underground Space Technology 28 (2012) 331-344) discloses a study on methods of finding water leak in various conduits.
However, the above patent and features mostly have the concept of a method of calculating a position according to an ultrasonic signal delay time but do not disclose a method of calculating the distribution range of an underground medium by utilizing an electromagnetic wave and ultrasonic signal.